The invention relates to an apparatus for manufacturing book covers.
Apparatuses of said type are known as book cover machines based on a horizontal processing principle, in which in a continuous pass cover boards and a spine insert are combined in a correctly fitting manner with the glue-coated covering material in a roll-on device. In successive work stations the projecting edges of the cover, either while in motion or while stationary, are folded, generally first at the edges projecting from the top and bottom and then, after drawing-in of the corners, at the sides. The book covers are then conveyed between press rollers of a pressing apparatus, in which separate systems rub the board covers and the spine insert onto the covering material. In a delivery station the book covers pass in the form of stacks over a roller table for manual removal.
The cover boards are stocked on a prestacking belt, from which they pass in streams or in stacks into a board feed hopper. The lowermost cover boards are pushed out of the feed hopper and supplied together with the spine insert on guide rails in a laterally aligned manner to the rolling-on device. As a spine insert, flexible roll screening cut to length and width in the machine or a cardboard strip previously cut to size may be used, which is introduced into the feed plane of the cover boards immediately prior to the rolling-on operation. In synchronism with the board feed, the covering material is brought by a covering material cylinder into the rolling-on plane. The covering material is decollated from a covering material feed hopper, optionally aligned and supplied by further conveying devices to the covering material cylinder, which takes over the covering material with grippers and conveys it past a glue spreading roller prior to the rolling-on operation.
In the previously known apparatuses the essential functions, such as the board feed, covering material feed, covering material cylinder and folding and pressing apparatus, are coupled directly to one another by a common drive. The functions of decollating the covering material and decollating the cover boards are switchable on and off. Feeding of the spine insert processed from the screening roll is effected by an individual drive controlled in a clocked manner. Further individual drives are assigned to peripheral functions, such as restocking the board feed hopper, stacking and delivering the finished book covers etc. As a result of the direct coupling of the drives of the main functions the entire book cover machine is stopped as soon as a fault arises in the region of the board feed or the covering material feed, and the book cover machine is not re-started until after the fault has been eliminated. Because of the long waiting period, book covers which are situated during said period in the folding apparatus are not durably glued together and have to be discarded as rejects. The result is a lower effective output.
In the known book cover machines the book covers are joined and moved forward in such a way that the leading edges of the boards and book covers are oriented by fixed reference edges, which is also known as conveying with a constant leading edge. The board feed pushes the cover boards and the spine insert towards the rolling-on device by acting on their trailing edge. The stroke position of said board pusher therefore has to be adapted to the book cover format by suitable adjustments, with the result that the board feed is complex and there is only a limited possibility of carrying out a necessary correction during operation. The folding width at the top and bottom of the cover is dependent upon the length difference between the covering material height and the cover board height and/or in some cases also upon the printing format of the covering material. Setting-up of the folding width as well as correction during operation are effected by means of an elaborate differential drive, which is connected in the drive train upstream of the covering material cylinder and the covering material feed and by means of which the covering material is supplied by its leading edge at an earlier and/or later time to the rolling-on device. The setting-up of a new book cover format is time-consuming and therefore reduces the effective output of the machine.